Ch22_PT
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) A carbohydrate can be defined as a molecule
A) composed of amine groups and carboxylic acid groups bonded to a carbon skeleton.
B) composed mostly of hydrocarbons and soluble in non-polar solvents.
C) whose name ends in "-ase".
D) that is an aldehyde or ketone and that has more than one hydroxyl group.
E) composed of carbon atoms bonded to water molecules.
1)
2) Classify the molecule shown according to the location of its carbonyl group and the number of
carbon atoms.
2)
A) ketotriose
B) ketotetrose
C) aldotetrose
D) aldopentose
E) aldotriose
3) Classify the molecule shown according to the location of its carbonyl group and the number of
carbon atoms.
A) aldotetrose
B) aldopentose
C) aldotriose
D) ketotriose
E) ketotetrose
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3)
4) Classify the molecule shown according to the location of its carbonyl group and the number of
carbon atoms.
4)
A) ketotriose
B) aldotriose
C) aldotetrose
D) aldopentose
E) ketotetrose
5) Glucose can be classified as a(an)
A) ketohexose.
B) aldopentose.
C) aldohexose.
D) ketopentose.
E) aldoketose.
5)
6) Ribose can be classified as a(an)
A) ketohexose.
B) aldohexose.
C) ketopentose.
D) aldopentose.
E) aldoketose.
6)
7) Fructose can be classified as a(an)
A) aldohexose.
B) ketohexose.
C) aldopentose.
D) aldoketose.
E) ketopentose.
7)
8) How many stereoisomers of an aldotetrose can exist?
A) 16
B) 32
C) 2
D) 4
E) 8
9) How many stereoisomers of an aldopentose can exist?
A) 2
B) 16
C) 8
D) 32
E) 4
10) Left- and right-handed mirror image molecules are known as
A) structural isomers.
B) enantiomers.
C) diastereomers.
D) anomers.
E) cis-trans isomers.
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8)
9)
10)
11) Molecules such as erythrose and threose, which are stereoisomers but not mirror images, are
referred to as a pair of ________. D- and L-threose are mirror images and are referred to as a pair
of ________.
A) anomers; diastereomers
B) diastereomers; anomers
C) diastereomers; enantiomers
D) enantiomers; diastereomers
E) anomers; enantiomers
11)
12) Which molecule shown is D-glyceraldehyde?
A)
12)
B)
C)
D)
E)
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13) A sugar is classified as a D-isomer if the hydroxyl group
A) on the chiral carbon nearest to the carbonyl points to the right.
B) on the chiral carbon farthest from the carbonyl points to the left.
C) on the end carbon farthest from the carbonyl points to the left.
D) on the chiral carbon farthest from the carbonyl points to the right.
E) on the chiral carbon nearest to the carbonyl points to the left.
13)
14) Which molecule shown is an L-isomer?
A)
14)
B)
C)
D)
E)
4
15) Which molecule shown is a D-isomer?
A)
15)
B)
C)
D)
5
E)
16) Two isomeric sugars that are cyclic and only differ in the position of the -OH group attached to the
hemiacetal carbon are called
A) eneantiomers.
B) anomers.
C) diastereomers.
D) mutarotations.
E) epimers.
16)
17) Mutarotation is process where
A) two glucose molecules react to form a disaccharide.
B) glucose undergoes reaction to form an equilibrium mixture of anomers.
C) glucose isomerizes to fructose.
D) glucose reacts with an alcohol forming a cyclic acetal.
E) the aldehyde group present in a sugar is converted to a hemiacetal.
17)
18) All of the statements concerning monosaccharides are correct except
A) A molecule is classified as a D or L isomer by the position of the hydroxyl group on the chiral
center farthest from the carbonyl group.
B) Monosaccharides have the general formula Cn (H2O)n , but this only describes the number
18)
and kinds of atoms, not their structure.
C) Monosaccharides with 5 or 6 carbon atoms exist in solution in cyclic form.
D) The number of stereoisomers possible is 2 n , where n is the number of chiral carbon atoms in
the molecule.
E) The two different cyclic forms of a particular monosaccharide are called tautomers.
19) The conversion of cyclic glucose between the alpha form and the beta form is called
A) dimerization.
B) hydrolysis.
C) polymerization.
D) cyclization.
E) mutarotation.
19)
20) When a monosaccharide forms a ring by interaction of one of its hydroxyl groups with its aldehyde
group, the bond is referred to as a(an) ________ linkage.
A) ester
B) glycosidic
C) hemiacetal
D) acetal
E) ether
20)
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21) A hemiacetal linkage consists of a
A) carbon atom bonded to two -OH groups.
B) carbon atom bonded to both an -OH and an -OR group.
C) carbon atom that is bonded to an -OR group and an -NH2 group.
21)
D) carbonyl group that is also bonded to a hydroxyl group.
E) carbonyl group that is also bonded to an ether linkage.
22) A sugar is classified as an L-isomer if the hydroxyl group
A) on the chiral carbon closest to the carbonyl group points to the right.
B) on the chiral carbon farthest from the carbonyl group points to the right.
C) on the chiral carbon closest to the carbonyl group points to the left.
D) on the end carbon farthest from the carbonyl points to the left.
E) on the chiral carbon farthest from the carbonyl group points to the left.
22)
23) All of the following are common monosaccharides of interest in human biochemistry except
A) glucose.
B) maltose.
C) ribose.
D) galactose.
E) fructose.
23)
24) Fructose is similar to glucose and galactose in all of the following aspects except
A) it forms a hemiacetal ring.
B) it can undergo mutarotation from α to β anomers.
C) its formula is C6 H12O6 .
24)
D) it is a ketose.
E) none of the above
25) When a monosaccharide forms a cyclic hemiacetal, the carbon atom that contained the carbonyl
group is identified as the ________ carbon atom because
A) D; the carbonyl group is drawn to the right.
B) anomeric; its substituents can assume an α or a β position.
C) L; the carbonyl group is drawn to the left.
D) acetal; it forms bonds to an OR and an OR'.
E) enantiomeric; depending on its position, the resulting ring can have a mirror image.
25)
26) reaction of a simple sugar with an alcohol produces a ________.
A) a mixture of anomers
B) cyclic acetal
C) glycoside
D) all of the above
E) none of the above
26)
27) ________ of glucose leads to gluconic acid.
A) Reduction
B) Oxidation
C) Isomerization
D) Esterification
E) Glycosidation
27)
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28) Common reducing reactions of monosaccharides are due to
A) the presence of more than one hydroxyl group.
B) the presence of at least one chiral carbon atom.
C) the presence of at least one hydroxyl group.
D) their cyclic structures.
E) the presence of a carbonyl group, usually on the #1 carbon atom.
29) Which molecule is not a reducing sugar?
A) glucose
B) galactose
28)
29)
C) lactose
D) sucrose
E) maltose
30) Which molecule is a reducing sugar?
A) starch
B) glycogen
C) amylopectin
D) maltose
E) sucrose
30)
31) Ketoses can act as reducing sugars in basic solution because
A) their carbonyl groups can readily be oxidized just as in aldoses.
B) mutarotation makes the carbonyl group accessible to oxidizing agents.
C) the large number of hydroxyl groups allows oxidation of the molecules.
D) the ketone is converted to an aldehyde by keto-enol tautomerization.
E) none of the above
31)
32) A glycosidic bond is
A) a bond between any two carbohydrate molecules.
B) a bond formed between an anomeric carbon atom and any OR group.
C) a bond between anomeric carbon atoms on two separate monosaccharides.
D) any bond that can be broken by reaction with water.
E) none of the above
32)
33) All of the following are functions of modified carbohydrate molecules except
A) As heparin they form a fibrous network in blood clots.
B) As a component of hemoglobin they transport oxygen.
C) As a receptor molecule on cell surfaces they assist in the functioning of the immune system.
D) As a component of cartilage they provide support to joints.
E) As chitin they act as a structural component of lobster shells.
33)
34) Cellulose is produced by ________, and its major function is ________.
A) animals; energy storage
B) plants; energy storage
C) animals; as a structural component
D) plants; as a structural component
E) none of the above
34)
35) The reaction in which a disaccharide is broken down into its component monosaccharides is
A) oxidation.
B) hydrolysis.
C) reduction.
D) glycoside formation.
E) enediol formation.
35)
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36) Lactose result from reacting glucose at its ________ carbon and galactose at its ________ carbon.
A) 6, 1
B) 4, 1
C) 1, 1
D) 1, 4
E) 1, 6
36)
37) The bond connecting the two monosaccharides in maltose is a(an) ________ linkage.
A) 1,2 anomeric
B) α-1,4 glycosidic
C) β-1,6 glycosidic
D) β-1,4 glycosidic
E) α-1,6 glycosidic
37)
38) The bond connecting the two monosaccharides in sucrose is a(an) ________ linkage.
A) α-1,6 glycosidic
B) α-1,4 glycosidic
C) β-1,6 glycosidic
D) b-1, 4 glycosidic
E) 1,2 anomeric
38)
39) The molecular formula of the common disaccharides in human biochemistry is
A) C12H22O11.
39)
B) C2 (H2O)2 .
C) C12H24O12.
D) CH2 O.
E) C6 H12O6 .
40) Sucrose is not a reducing sugar because its
A) disaccharide bond is a β-1,4 linkage.
B) disaccharide bond is an α-1,4 linkage.
C) hemiacetal groups cannot be converted to aldehyde groups.
D) disaccharide bond is a 1,2 anomeric link.
E) none of the above
40)
41) Glocoproteins are formed by bonding a oligosaccharide to a protein through a ________ linkage.
A) glucuronic
B) ester
C) ether
D) glycosidic
E) imine
41)
42) Starch is produced by ________, and its major function is ________.
A) animals; energy storage
B) animals; as a structural component
C) plants; energy storage
D) plants; as a structural component
E) none of the above
42)
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43) Glycogen is produced by ________, and its major function is ________.
A) plants; as a structural component
B) animals; as a structural component
C) plants; energy storage
D) animals; energy storage
E) none of the above
43)
44) Starch is composed of two polymers, ________, which is an unbranched chain, and ________, which
is a branched polymer.
A) amylase; amylose
B) amylose; amylase
C) amylopectin; amylose
D) amylose; amylopectin
E) amylase; amylopectin
44)
45) Which of the following statements comparing amylopectin and glycogen is false?
A) Both are polymers of α-D-glucose.
B) Both serve as energy storage molecules.
C) Glycogen is more highly branched than amylopectin.
D) Glycogen molecules are generally larger than amylopectin molecules.
E) none of the above
45)
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
46) Explain why cows and other grazing animals can eat grass and benefit from its nutritive
value, but humans cannot.
46)
MATCHING. Choose the item in column 2 that best matches each item in column 1.
Match the following.
47) enantiomers
A) a monosaccharide that is sweeter than
sucrose and found in honey and fruits
48) diastereomers
49) anomers
50) galactose
51) ribose
52) fructose
B) an aldopentose that is a component of
nucleic acids
C) stereoisomers that are not mirror images of
each other
D) a monosaccharide which is a component of
milk sugar
47)
48)
49)
50)
51)
52)
E) mirror-image forms of chiral molecules
F) isomers of cyclic sugars that exist in the
position of the hydroxyl group at the
hemiacetal carbon atom
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53) glucose
A) a monosaccharide that functions as the
transport form of carbohydrates in blood
54) reducing sugar
55) polysaccharide
56) sucrose
57) maltose
58) lactose
59) disaccharide
60) amylose
61) cellulose
62) glycogen
B) a polysaccharide composed of glucose
units joined by β-1,4 linkages
C) a disaccharide composed of one molecule
of glucose and one molecule of galactose
D) a disaccharide composed of two molecules
of glucose
53)
54)
55)
56)
57)
58)
E) a very highly branched polysaccharide
composed of glucose units
F) a component of starch composed of
glucose units joined by β-1,4 linkages
59)
60)
61)
G) a carbohydrate that yields two
monosaccharides upon hydrolysis
H) a carbohydrate composed of a large
number of monosaccharides chemically
combined
I) a carbohydrate that can be oxidized to
produce an acid molecule or its
corresponding anion
J) a disaccharide composed of one molecule
of glucose and one molecule of fructose
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62)
Answer Key
Testname: UNTITLED1
1) D
2) C
3) E
4) D
5) C
6) D
7) B
8) D
9) C
10) B
11) C
12) A
13) D
14) D
15) E
16) B
17) B
18) E
19) E
20) C
21) B
22) E
23) B
24) D
25) B
26) D
27) B
28) E
29) D
30) D
31) D
32) B
33) B
34) D
35) B
36) B
37) B
38) E
39) A
40) D
41) D
42) C
43) D
44) D
45) E
46) Humans do not have the enzyme that breaks the β-1,4-linkages in cellulose. Grazing animals and some insects have
bacteria in their digestive systems that produce an enzyme that hydrolyzes these linkages. Therefore these animals can
digest and metabolize cellulose.
47) E
48) C
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Answer Key
Testname: UNTITLED1
49) F
50) D
51) B
52) A
53) A
54) I
55) H
56) J
57) D
58) C
59) G
60) F
61) B
62) E
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